Meccano LTD Hornby II Power control Unit

Found while clearing out the last of dad's estate.

The fact is says Mecanno thought should try to sell on trade me in case there is a collector out there who wants one of these units

I have absolutely no idea how you tell if it works or not.

Refer photos

Measuerements 11 cms wide 18 cms length 5 1/2 cms deep

Pick up is Mt Eden or if posting I won't know how much it will cost until it sells.